Reproduction

therefore essentially determines the final shape and size of the spermatophore. After spermatophore formation, the sac is withdrawn. Rhodnius, some Coleoptera, and some Diptera form spermatophores in this way. The two remaining methods are female-determined. In the first, seen in Trichoptera, Lepidoptera, some Diptera, some Coleoptera, and a few Hymenoptera, male accessory gland secretions empty directly into the vagina or bursa in a definite sequence, either before or after transfer of sperm which they encapsulate. The spermatophore takes up the shape of the genital duct. The spermatophore produced by the second female-determined method is the least complex. Male accessory gland secretions are produced concurrently with or immediately after sperm transfer and often do not encapsulate the sperm; rather, they harden to form a mating plug that prevents backflow and loss of semen (and also, further mating). This method is seen in mosquitoes, the honey bee, and some Lepidoptera. Gerber (1970) speculated that the next step in the evolutionary sequence would be complete loss of the spermatophore and, concurrently, the development of a more elongate penis for depositing sperm close to the spermatheca.

The number of spermatophores formed, the length of time the spermatophore remains with a female, and its fate are varied. In some species a male produces a single spermatophore during each copulation, and this may remain in the female's genital tract or between the genital plates for several hours to ensure complete evacuation of semen. Empty spermatophores are generally discarded. However, as noted earlier, they may be eaten by the female, or partially to completely digested within her genital tract, thus providing a nutrient contribution toward egg production.

Precisely how sperm move from the spermatophore to the spermatheca is for most species unclear, In some species the anterior end of the spermatophore is open to facilitate the escape of sperm. Where the spermatophore completely encloses the sperm, its wall may be either ruptured by spines protruding from the wall of the bursa or digested by secretions of the bursa wall or accessory glands. Transfer of sperm into the spermatheca is achieved normally as a result of rhythmic contractions of the reproductive tract. In Rhodnius the contractions are promoted by a substance contained within the seminal fluid and produced in the male's accessory glands. In some species sperm may migrate actively into the spermatheca, possibly in response to a chemotactic stimulus released by the storage organ.

Insemination Without a Spermatophore. In species where spermatophores are not used in insemination, the penis may be rigid and erection achieved by means of muscles. In such instances the organ penetrates only a short distance into the female's genital tract. Alternatively and more commonly, the penis is thin-walled and erected by hydrostatic pressure, either of the hemolymph or of fluid contained within a special reservoir off the ejaculatory duct. It extends far into the genital tract of the female and terminates adjacent to the spermatheca.

In Odonata, where a unique mode of sperm transfer is found, the male copulatory organ is a tubular structure formed on the third abdominal sternum. Prior to mating, a male transfers sperm to the copulatory organ by coiling the abdomen ventrally. During mating (which occurs in flight), the female, held around the head or prothorax by the male's terminal claspers, brings the tip of her abdomen into contact with the copulatory organ (Figure 6.9). Remarkably, in damselflies and some dragonflies the male's copulatory organ, which is equipped with horns and/or spines, not only transfers sperm to the female but first removes sperm deposited in a previous mating (Waage, 1979, 1986). In other dragonflies the copulatory organ has an inflatable head that is used to push previously deposited sperm

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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